The use of synchronous motors with direct start and permanent magnets from the mains (LSPMSM) makes it possible to increase the efficiency of standard installations driven by electric motors with direct start from the mains, such as pumping and fan installations. Such motors have increased efficiency compared to asynchronous motors and do not have an excitation winding compared to classical synchronous motors with an excitation winding. However, LSPMSM have difficulties with starting installations with a large moment of inertia. This problem may be aggravated by a decrease in the supply voltage and a voltage drop on the cable. This article is devoted to the evaluation of the success of synchronization of LSPMSM as part of a centrifugal pumping unit, taking into account the reduced value of the supply voltage and the influence of the cable. The success of engine synchronization is determined using a model with concentrated parameters, due to the simplicity of model compilation and less time spent. The parameters for such a model can be determined as a result of engine tests or by calculation if the details of the engine design are known. To obtain the results of this study, the processes of starting four-pole LSPMSM in centrifugal pumping units of various capacities: 0.55 kW and 3 kW are considered. The simulation results showed that LSPMSM has no problems with starting the pumping unit even with a decrease in the value of the supply voltage. The conclusion of this work can be used when choosing an electric motor to drive a pumping unit and contributes to the wider use of energy-efficient electric motors.